We have a fleet of 14 2007 models at work, 4 are 4500 series, the rest are 6500 series.
I'm the Fleet Manager so the maintenance records land on my desk, so far they've been warranty nightmares.
The highest mileage is 72K and the lowest mileage is 12K, we took delivery of all 14 brand new in October of 2006. Our company purchased 268 Top Kick trucks nationwide for FY 2006.
Heres a short list of the problems we've had so far:
8 trucks had headlight harnesses replaced.
3 had ignition harnesses replaced.
2 have issues with repeat warning lights on the dash that cant seem to be repaired.
14 have had the cruise control repaired (all 14 are broken again).
12 had to have the A/C recharged at the begining of summer (and need it recharged again).
The center console has broken loose from the floor on all 14.
6 have had the air ride system repaired for leaks that cause the pump to continuously run and wear down the battery (4 now have the pump power wire unhooked and only connected when needed).
5 trucks have leaking windshields that cant seem to be repaired.

The trucks ride and handle good.
Getting on the freeway with a load (usually around 3 tons for us) is slow. Unloaded they do ok.
Braking is good for a truck this size.
Visibility from the drivers seat is ok, the mirrors need to be moved farther out on the fenders towards the nose of the truck.
Passengers seat needs an arm rest.
The trucks are better than the competitors offerings in ride and drive, it's the maintenance issues that have been hurting us. I've had some weeks with 3-4 trucks down at one time.

Thanks Steve, I noticed that you were at one time looking to get input from those who drive/own Topkicks. Did you were get the input you needed to write your review? I just picked up from a dealer in St. Louis who had it advertised in Truck Paper.com

The truck was on the ground and customized by Monroe Truck Equipment fully loaded, the only problem that I found was that it was ordered without a air filter minder, trans gauge and no center console which will be taken care of in due time.

I previously had a 2002 Silverado 2500HD loaded with Banks Power equipment, six gun tuner, exhaust brake and monster exhaust pipes. That truck was excellent to me, plenty on power but the chassis was not rated to tow the 16.5 plus pounds that my 5th wheel weighs... so I had to move up to a 4500 chassis.

The 5th wheel is winterized right now so I haven't had a n opportunity to hook it up. I might hook it up my horse trailer but that will not be a good test since my old pick with 300 ph duramax had no problems pulling that.

I looked at every option of truck out there for over a year and decided on a topkick/Kodiak...the Topkick I found in St. Louis on paper was just right for my pocket book.

MPG was important since I got pretty good MPG for a full size HD truck...17-19 around town and 21-22 on the highway. So, since the only truck today 1/09 that is 2010 complaint is the Ram 4500, had to be cusotmized as well with pickup body by Warner Bodies... I looked at truck customized by MTE. I'm please to say that my new Topkick is getting 13 MPG around twon and coming by from St. Louis (1000 mile trip back home) I got 16 MPG unloaded. I suspect I will get 10-11 MPG which is what I got with my old Silverado. So If that;s the case than I should be able to squeeze a couple of more miles by adding a high perforamce air filter, wind deflector more Banks Power equipment after the warranty are done with. By that time the engine will be broken in and MPG shoul dbe improved.

The key for me was to find a 4500 midsize truck rated to tow my needs that had a pickup body! Eventhough the Ford 450 was prefect looking for a "off the line" truck the more I readed and Googled what was going on with that truck with the new engine and all the people that I spoke to while on the road I decided to stay away. I figure if the Duramax Allison combination hadn't failed me ...why change. I hope I don't eat my words.

Thanks, I've been looking at what GM and everybody could possibly be coming out with for 2010 in the 4500 type turck, and with all the troubles GM has been having, I didn't know what the future was going to be for them or anybody else for that matter. There was talk that GM midsize trucks was going to be sold to International which would OK for me since they're a truck company. Ford's 450 which looks great didn't have a duramax or allison trans. Dodge cost too much to but a pickup body on it and Freightliner M2 class truck are way over priced.

There is also talk that GM would come out with a production 4500 style pickup body like Dodge and Ford have done, but that wouldn't have been available until next year. So, I thought since it's a buyers market right now that I pull the trigger on what I know to be solid ( I hope).

I'll be keep on eye on what GM will be doing to meet 2010 emssion complaince. There is enough chatter on the web that GM will be increeasing the Duramax HP to a 6.9L or 7.0L (400HP) and add more gears to their Allison Trans. In any case, I will not be an early adopter until maybe 2013-2014. It's all going to be interesting

I setup an album there are several pics there... I have driven non air ride Kodiak in class C motorhomes and it's not something you want to sign up for. My old Silverado road really nice...I liked the ride best out of all the pickup out there. Coming from driving Motorhomes i.e. Monaco Windsor with 8 air bags...I knew that buting Link's CabMate and Link's rear suspension which air ride seat was estential. I got lucky to find a truck on the ground spec'd out the way I wanted eventhough I had to drive 1000 to get it in an ice storm this month.